1. Field of the Invention
This application pertains to a particle separation method and apparatus.
More particularly, the invention relates to an apparatus and method for separating dielectric particles.
In a further respect, the invention relates to particle separation apparatus and method which reduce the risk that a fire or explosion will occur during the separation of particulate.
In another respect, the invention relates to a particle separation apparatus and method which facilitates the separation of elongate fiber strands from a plurality of small substantially round particles.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A wide variety of particle separation apparatus is apparently known in the art. One such particle separation apparatus is illustrated in FIG. 1 and includes a cylindrical steel roller 10 which rotates in the direction of arrow E about axle 42. A hopper 11 feeds a mixture of electrically non-conductive 12 and electrically conductive particles 13 onto the cylindrical outer surface or roller 10. The size of the particles is greatly exaggerated for purposes of clarity. The positive side of the power supply is connected to the roller 10. The roller 10 is grounded. An elongate wire 14 is spaced apart from and parallel to the cylindrical surface of roler 10. The wire 14 serves as the negative electrode. A large voltage is directed through wire 14 to produce a corona around the wire. Negative ions move through the field produced by the wire to roller 10. The conductive particles 13 conduct negative ions to roller 10. Consequently, the conductive particles 13 fall off the surface of roller 10 or are thrown off roller 10 into bin 16. In contrast to the conductive particles 13, negative ions are believed to accumulate on the outer surface of each non-conductive particle 12 to cause each particle 12 to be attracted to the positively charged roller 10. The negatively charged non-conductive particles are scrapped off by scraper 43 into bin 15. Several disadvantages are associated with the apparatus of FIG. 1. First, the high voltage required to form a corona around wire 14 increases the risk of explosion or fire during the separation of particulate. Second, while the apparatus of FIG. 1 is well suited for the separation of conductive and non-conductive particles, it ordinarily is not believed well suited for separation of two types of conductive particles (for instance copper and silver particles) or for separation of two types of non-conductive particles (for instance rubber and paper particles).
Accordingly, it would be highly desirable to provide an improved particle separation apparatus and method which would significantly minimize the risk of fire or explosion and which could be utilized to separate dielectric particulate.
Therefore, it is a principal object of the invention to provide an improved method and apparatus for separating particles.
A further object of the invention is to provide an improved method and apparatus for separating dielectric particles.
Another object of the invention is to provide an improved particle separation method and apparatus which minimizes the utilization of energy at levels which increase the risk of fire.
Still a further object of the invention is to provide an improved particle separation method and apparatus which can distinguish between particles of differing size and triboeletric propensity.